Aah ! 'Got you now. The extractor rim - yes ?
Some cartridge makes have wider rims than others. Some rifles have extractor claws set closer to the bolt face than others, and some have deeper seating claws.
Maybe think about your brand of ammo and if you can - compare it with another brand
Also perhaps get your extractor claw looked at. If it's too tight it can perhaps be relieved without detracting from it's extraction efficiency.
ALSO, there might be a variation of pressure during feeding the cartridge into the chamber from the magazine. (First cartridge to last). The base of the round should slip into the bolt face sweetly and not be obstructed by a sharp - deep or tight extractor claw. The problem might start right there.
A combination of weak magazine spring and stiff extractor can make for poor chambering in some instances.
It might be worth paying attention to when and if you feel a stiff cartridge going in.
I don't know if you've come across the problem, but it's often the case that with the old fashioned mauser action, the extractor claw would slip into place easily over a previously chambered round, but some later copies would not and this was probably dependent on the way they were machined and shaped.
I've spent an hour or two with a fine grinder and rectified difficult chambering in the past.
'Sorry to get your meaning wrong at the start. Not all extractor rims are machined out to precision, and I know of several brands which were a bit guilty of that at times.
As long as the case extracts OK afterwards, I see no problem with removing the inside rim burrs if they are not cut too deep.